Two words - human nature.
It is an inbuilt reaction in human beings to try and paint themselves in the best light possible, even in the light of masses of evidence to the contrary.
Reports at the time confirm that the captain did not abandon his ship, he 'fell off'' - and how a similar lapse in balance caused him to 'fall into' a taxi at the quayside and disappear rapidly as the tragedy unfolded.
But even so, his human nature and it's instinct to try and make himself look better is still firing on all cylinders - he appears full of both self-obsession and self-pity, given what the world knows took place on the awful day.
But he will continue to try and place the blame elsewhere for the simple reason that if you can make it someone else's fault, it doesn't have to be your fault, and you can live with yourself a little better.
I don't for a moment think that the captain's view of events is going to save him from a sentence that reflects his culpability, but he will die denying that it was his fault.